So this character I decided to use a mage/shortsword guy altmer, with the atronach birthsign.

but the atronach is giving me some trouble. how can i keep my magic up? restore magicka potions are difficult to come by, and the ingredients to make it are even more difficult to find, at least at my low level.

thanks guys

You need to get your Alchemy to the point where you can make potions worth 100g or more. You can speed this up by fortifying Alchemy (if you have Tribunal) or fortifying Intelligence either with a spell or by making potions( keeping in mind that some players consider potion stacking an exploit, you'll have to decide for yourself).

At that point, you can make lots of potions and basically trade them for frost salts and comberry to make restore magicka potions. It's tedious but it works and it really builds Alchemy quickly.
If you can get to Balmora, you can do this right at level 1. If you want a detailed run through, ask in the hints forum.

Shrines and weak magic using enemies are your friend at this stage.

Ancestor Ghosts can be used to get some magic back in - and since they dont pose a thread at all if encountered by themselves, you might want to look into a summoning spell or an enchanted item with the same effect. Honestly, it is the best way to recharge on the run.

Also, learn to love Intervention spells. Either a Rilms Shrine at the tempel with the according blessing or a imperial cultist shrine (restore skills) will fully recharge your magicka. Consider joining the tribunal temple and the imperial cult so you wont need to donate money every time you visit a shrine.

I RARELY ever needed to chuck down a restore magicka potion with my latest atronach playthrough . In the early stages I went around killing things with a summoned spear to pump endurance (thus never needed a lot of magic) and later on you will have a good magicka pool to spent.

PS: Get the Necromancer's Amulet asap.

Vampires make good atronach mages. Summon a ghost, have it recharge your magicka, and use your nice cheap drain health spell when you need healing.

Works a charm.

As was said, you can absorb shrine blessings. Mark & Recall in combination with Divine or Almsivi Intervention work very well. Especially if you have all spells available as cast-when-used enchantments.